Evidence for a phenotypic switch in corneal afferents after lacrimal gland excision.

Dry eye is a common cause of ocular pain. The aim of this study was to investigate corneal innervation, ongoing pain, and alterations in corneal afferent phenotypes in a mouse model of severe aqueous tear deficiency. Chronic dry eye was produced by ipsilateral excision of the extra- and intraorbital lacrimal glands in male and female mice. Tearing was measured using a phenol thread and corneal epithelial damage assessed using fluorescein. Changes in corneal ongoing ocular pain was evaluated by measuring palpebral opening ratio. Corneal axons were visualized using Nav1.8-Cre;tdTomato reporter mice. Immunohistochemistry was performed to characterize somal expression of calcitonin gene-related peptide (CGRP), the capsaicin sensitive transient receptor potential vanilloid 1 (TRPV1), and activating transcription factor-3 (ATF-3) in tracer labeled corneal neurons following lacrimal gland excision (LGE). LGE decreased tearing, created severe epithelial damage, and decreased palpebral opening, indicative of chronic ocular irritation, over the 28-day observation period. Corneal axon terminals exhibited an acute decrease in density after LGE, followed by a regenerative process over the course of 28 days that was greater in male animals. Corneal neurons expressing CGRP, TRPV1, and ATF3 increased following injury, corresponding to axonal injury and regeneration processes observed during the same period. CGRP and TRPV1 expression was notably increased in IB4-positive cells following LGE. These results indicate that dry eye-induced damage to corneal afferents can result in alterations in IB4-positive neurons that may enhance neuroprotective mechanisms to create resiliency after chronic injury.

Lacrimal gland excision in male and female mice causes ocular pain and anxiety-like behaviors.

Lacrimal gland excision (LGE) induced dry eye produces more severe corneal damage in female mice, yet signs of LGE-induced ocular pain and anxiety in male and female mice have not been characterized. Excision of either the extraorbital gland (single LGE), or both the extraorbital and intraorbital glands (double LGE) was performed in male and female C57BL/6J mice to induce moderate and severe dry eye. Ongoing pain was assessed by quantifying palpebral opening and evoked nociceptive responses after corneal application of capsaicin and menthol. The open-field and plus maze were used to assess anxiety. Single LGE caused a reduction in palpebral opening and an increase in capsaicin and menthol-evoked responses only in female mice. Furthermore, single LGE produced signs of increased anxiety in female but not male mice. Overall, female mice appear more susceptible to signs of ocular pain, irritation, and anxiety in response to aqueous tear deficiency.

Evaluation of Corneal Damage After Lacrimal Gland Excision in Male and Female Mice.

Purpose: Lacrimal gland excision (LGE) has been utilized in several studies to model aqueous tear deficiency, yet sex as a biological variable has not been factored in to these reports. This study compared corneal pathology in male and female mice following LGE-induced dry eye. Methods: An LGE of either the extraorbital lacrimal gland (single LGE) or both the extraorbital and intraorbital lacrimal glands (double LGE) was performed in male and female C57BL/6J and Balb/cJ mice to produce dry eye of graded severity. Following excision, tearing was evaluated with phenol red thread, and corneal fluorescein staining was scored to quantify the severity of damage. Corneas were evaluated for apoptosis by the TUNEL assay and for cell proliferation using Ki67 staining. Furthermore, corneas were harvested and analyzed for macrophages via flow cytometry. Results: Baseline tearing levels were similar in male and female mice, and LGE resulted in comparable reductions in tearing with the lowest levels recorded after double LGE. As determined by fluorescein staining, LGE produced more severe damage to the cornea in female C57BL/6J and Balb/cJ mice. Double LGE increased TUNEL and Ki67 staining in the cornea, with greater increases found in female mice. Furthermore, LGE produced a greater increase in the total number of corneal macrophages in female mice. Conclusions: These results indicate that female mice are more susceptible to LGE-induced corneal damage. The mechanisms involved in producing these sex differences still need to be elucidated but may involve increased inflammation and macrophage infiltration.

Exploitation of Mangrove Endophytic Fungi for Infectious Disease Drug Discovery.

There is an acute need for new and effective agents to treat infectious diseases. We conducted a screening program to assess the potential of mangrove-derived endophytic fungi as a source of new antibiotics. Fungi cultured in the presence and absence of small molecule epigenetic modulators were screened against Mycobacterium tuberculosis and the ESKAPE panel of bacterial pathogens, as well as two eukaryotic infective agents, Leishmania donovani and Naegleria fowleri. By comparison of bioactivity data among treatments and targets, trends became evident, such as the result that more than 60% of active extracts were revealed to be selective to a single target. Validating the technique of using small molecules to dysregulate secondary metabolite production pathways, nearly half (44%) of those fungi producing active extracts only did so following histone deacetylase inhibitory (HDACi) or DNA methyltransferase inhibitory (DNMTi) treatment.